Question

A stone is thrown straight down from the edge of a roof, 1200 ft above the ground, at a speed of 9 ft/sec. A. Given that the acceleration due to gravity is -32 ft/sec2, how high is the stone 2 seconds later?

Answer 1

Answer, d' = 1118 meters

Step-by-step explanation:

Given that,

The stone is thrown straight down from the edge of a roof, h = 1200 ft

Speed of the stone, u = 9 ft/s

The acceleration due to gravity is,
`a=-32\ ft/s^2`

Time, t = 2 s

Let d is height reached by the stone in 2 seconds. It can be calculated using second equation of motion as :

`d=ut+(1)/(2)at^2`

Here, a = g

`d=ut+(1)/(2)gt^2`

`d=9* 2+(1)/(2)* 32* 2^2`

d = 82 m

So, the height of stone after 2 seconds is,

d' = 1200 - 82

d' = 1118 meters

Hence, this is the required solution.